User-friendly, low-cost equipment for preventive screening of severe or deadly pathologies are one of the most sought devices by the National Health Services, as they allow early disease detection and treatment, often avoiding its degeneration. In recent years more and more research groups are developing devices aimed at these goals employing gas sensors. Here, nanostructured chemoresistive metal oxide (MOX) sensors were employed in a patented prototype aimed to detect volatile organic compounds (VOCs), exhaled by blood samples collected from patients affected by colorectal cancer and from healthy subjects as a control. Four sensors, carefully selected after many years of laboratory tests on biological samples (cultured cells, human stools, human biopsies, etc.), were based here on various percentages of tin, tungsten, titanium, niobium, tantalum and vanadium oxides. Sensor voltage responses were statistically analyzed also with the receiver operating characteristic (ROC) curves, that allowed the identification of the cut-off discriminating between healthy and tumor affected subjects for each sensor, leading to an estimate of sensitivity and specificity parameters. ROC analysis demonstrated that sensors employing tin and titanium oxides decorated with gold nanoparticles gave sensitivities up to 80% yet with a specificity of 70%.

Despite the great progress in screening techniques and medical treatments, colorectal cancer remains one of the most widespread cancers in both sexes, with a high death rate. In this work, the volatile compounds released from human colon cancer tissues were detected by a set of four different chemoresistive sensors, made with a nanostructured powder of metal-oxide materials, inserted into an innovative patented device. The sensor responses to the exhalation of a primary cancer sample and of a healthy sample (both of the same weight, collected during colorectal surgery from the intestine of the same patient) were statistically analyzed. The sensors gave reversible, reproducible, and fast responses for at least one year of continuous use, making them quite superior in respect to the existing diagnostic methods. Preliminary results obtained using principal component analysis of the sensor responses to samples removed from 13 patients indicate that the nanostructured sensors employed in this study were able to distinguish between healthy and tumor tissue samples with coherent responses (the discrimination power of the most sensitive sensor was about 17%), highlighting a strong potential for clinical practice.